experience with Metal Halide?

[Joseia]

Originally Posted by mexorchid

Thanks everybody for your input!
Naoki, very much like your table
Joseia, do you also find your MH light is using a very lot of electricity? What kind of reflector are you using?
A lot of heat wouldn't be bad because the orchids are standing on a heated platform filled with hydroton and water. I guess with more heat from the top there will just be more evaporation? I already have a fan and could mount it a bit closer to the light.
Good tip with the water sprays on the bulb, haven't thought of that!!!

I actually have not noticed a big increase in our electricity bills. But that could be because I changed most of our indoor house lights to more energy efficient LEDs around the time I started using the MH light. I am using a cheap open reflector, but f I were buying now, I would by one that could be enclosed with a glass cover below the bulb to ensure that no water could ever reach the bulb. If you do this, you might have to look at venting the heat that will build up inside an enclosed reflector.

I think the heat the light puts out works very well for me. Under the lights, the temperature around the orchids is about 6 degrees higher than ambient room temperature. I run a humidifier near the plants with a fan, and when the MH light goes off, the temperature drops nicely and I end up seeing a day/night temperature change from 82 to 73.

Yes, the plants definitely dry out faster under the MH light, I had to increase my watering frequency by one day to make up for the heat and increased evaporation.

[naoki]

Since I don't want to waste electricity (expensive here), I put all of the light source close to the plants. But with lens + LED, you can do something like David's set-up without wasting lots of energy. Close positioning of light (with wider beam pattern) has a "small" advantage that the lower leaves don't get shadowed, I guess.

I haven't made DIY LED, but if you know how to DIY, it is probably the most interesting route. When I calculated the cost with high quality LEDs, it wasn't that cheap (>$1 per actual W), though. For Catt, 40W/sqft (actual draw) is probably a good starting point. The light level of Catt is similar to that for marijuana.

I use LEDs only for low light orchids (Phal, Paphs), they flower/grow well with 10W/sqft (red+blue grow light, but I'm probably going to add a little more Cree or Phillips household LED bulbs).

People seem to get decent growth with white+red type LED grow light. area51 is one of W+R grow light with a good reputation.

[Joseia]

Great links naoki, thanks! I just checked the light levels with a meter, and it varys from about 750 directly under the MH light, and down to 600 around the edges. I am new to this, so time will tell if that light will be sufficient for the other catts to bloom. I hope so!

As to what kind of lights to get, LEDs, T5s or MH? They all have their own set of advantages and disadvantages. The T5s will work well for compact plants that are mostly about the same height. Much less heat with the T5s and probably easier to deal with than MH. But the MH is great for taller plants and better for a group of plants of varying heights. I also use some LEDs for certain plants. A mix of lights works well for me in my conditions since I also grow a variety of other houseplants.

[mexorchid]

Very interesting to hear about some actual real life experience with the different lights!

Originally Posted by naoki

I use LEDs only for low light orchids (Phal, Paphs), they flower/grow well with 10W/sqft (red+blue grow light, but I'm probably going to add a little more Cree or Phillips household LED bulbs).

naoki, the 10W/ft2, is that the only light source for the phals or is there some daylight too?

The topic is so interesting; I have been researching all evening and decided to start with LED, see how it goes before investing in an MH light.
I found heatsinks to mount 25x3W LEDs, drivers for 18 & 6 LEDs. I would go with 6 warm white, 7 cold white (I find they actually give a lot of blue light and some red spectrum of around 600), 2 red of 660nm, 1 blue, 2 green (the white doesn't have much green and I found a lot of info that the plants need apart from a lot of red and much blue also most of the other colours of the spectrum to be completely happy); Plus on the same heatsink an extra circuit of 1 blue, 1 red 620nm, 4 red 660nm that runs when I'm not home and I don't see the ugly red.
A setup similar to our aquarium light (pics) but different colours and a nicer enclosure.
Please add your opinion and suggestions! Do you think I should install also 1xUV LED? There is not much but still some natural light from the north window.
Thanks

[DavidCampen]

If you plan to place the LED fixture a siginficant distance above the plants then you will want lenses to focus the light.

[The Orchidist]

I am glad this thread is alive as i just setup my collection under a 400 MH , with parabolic shade . under the collection of plants is a temp of 25 to 26 celsious .
I had wondered if my plants were to close but my closest would be my catellaya at just over 16 inches . And i have a total of 13 to my collection ..None are near flowering except my newest addition catalaya which is in Bud mode and should open by end of November .

Goodluck on your choice of Lighting mexorchid All i know is that its working good for me so far .

[naoki]

Originally Posted by mexorchid

naoki, the 10W/ft2, is that the only light source for the phals or is there some daylight too?

I use a grow tent to deal with humidity issue. It is reflective inside, and completely block the natural light. So the artificial light is the only source. For higher light orchids, I still use T5HO.

LED (or any light) spectrum affects two aspects; photosynthesis and photomorphogenesis (the shape of plants). For example, red is efficient for photosynthesis, but it causes elongation. Blue causes reduction in leaf expansion (smaller leaves). In some plants, UV can influence the photomorphogensis (this doesn't seem to be the case for all plants). The benefit of green light has been shown recently, but this appear to be for high light plants (e.g. vegetables). Green light penetrates into the lower layer of cells for photosynthesis, so additional green light can be beneficial when the photosynthesis is close to saturation with red and blue.

Optimizing the spectrum is probably species specific, and it is not straight forward. I'm sure lots of people have different opinions. I've been reading about this topic, but I'm not sure what would be great for orchids. If I were you, I would probably go with white + red (since you don't want blue+red, which is my choice). area51 uses Cree XP-G Outdoor white: Cree XP-E red=2:1.

The 3rd link here is a related topic:
LED related links
It's from an experiment measuring the effects of different color LEDs.

Your aquarium light looks nice. 25x3W is probably less than 50 actual W, so you'll need quite a few of them to provide Catt level PAR for your area.

Nice setup, sg2100. It looks like you can put lots more orchids there!

[mexorchid]

That 25x3W LED is only 50W in real life is quite disappointing to hear

Originally Posted by DavidCampen

If you plan to place the LED fixture a siginficant distance above the plants then you will want lenses to focus the light.

I checked out already lenses for star LEDs. I think 30degree would be appropriate if I hang it 70cm over the plants.

I did more reading on the links naoki has posted. The 2 of you seem to be quite knowledgeable on the topic and I very much appreciate to get all these tips from the pros - thanks

[Nexogen]

If you don’t have a grow tent I don’t think it’s a good idea to use LED, this high intensity and color lights can be even more disturbing than the flashlights.

[mexorchid]

Originally Posted by Nexogen

If you don’t have a grow tent I don’t think it’s a good idea to use LED, this high intensity and color lights can be even more disturbing than the flashlights.

hmmmm... by now I'm very insecure of what to get! so many pros and cons.
Our aquarium LED light is not disturbing. As long as you make a big enough enclosure towards the room it doesn't blind at all. But I am worried about how the colours look like. I did some testing with 1W LEDs we have at home and 3 white ones couldn't overcome the red effect of 1 red LED. Thus the idea to make 2 circuits and have the colours on while I'm at work.
In colour render charts I see HPS would be the best but it looks ugly too. MH is good. Different white LEDs seem to have quite some blue and red already, so can it be so bad? With additional red for some hours... Could that be enough???
Feeling wise: if there is a method to save electricity I should do it. Not only for the valet but for the environment. It's gonna run many hours for many years.